Does stock fuel pump fall behind consumption?

[tdskip]

Hi guys - was looking at a Mini tech magazine and they had an article on fuel pumps. They suggested that cam driven pumps aren't capable of keeping up on modified/high performance engines.

Any truth to that on our TRs?

 

[SkinnedKnuckles]

I've not had any problem with a pump in good condition. That's with triple Z-S, GP2 cam, 1:1.55 RR, & about 9.3 compression.

Fuel filters, on the other hand, are a whole other issue...

 

[tinman58]

I would'nt think so. My engine is slightly modified and the carbs were running REAL rich. Black soot on the back of the car, smell of fuel out the tail pipe, The car ran good, but then a friend was behind me and we almost choked him to death going up to Mt. Hamilton. He complained and we adjusted the carbs leaner, ALOT. My point is that I think that the cam driven pumps will pump enough fuel no matter what. Race engines might be another story.

 

[Twosheds]

Kas Kastner told me that a TR3 race engine needs at least 15 gallons per hour flow.

Kas said it.

I believe it.

That settles it.

 

[tdskip]

Kas Kastner told me that a TR3 race engine needs at least 15 gallons per hour flow.

Kas said it.

I believe it.

That settles it.

Wow - that is a lot of fuel.

Will a stock pump do that?

 

[Twosheds]

Wow - that is a lot of fuel.

Will a stock pump do that?

I dunno. It wasn't too hard to measure the flow of my electric pump, but measuring the flow from a stock pump would seem to be a little harder to do. Especially at max RPMs.

 

[TR3driver]

15 gph doesn't seem like all that much, to me. 15*4 = 60, so that is a quart a minute, or 30 seconds for a pint ... that's about the standard I use for checking the stock pump at idle. I'm pretty sure it will deliver a lot more than that at higher rpm.

 

[DougF]

I'm using 3 Strombergs, all at stock factory settings with no problems. When tuning the carbs, at one point, they were all set very rich and I had no concerns. But I'm using a bit less than 15 gpm.

 

[TomMull]

I've never measured flow, although I'm sure Randall is correct and I agree that the stock diaphragm pump is adequate for street conditions. I also agree that it is fair to assume that the pump will be even more efficient at higher rpm - to a point. I don't know what that point is (certainly greater than 5000) but at very high rpms the diaphragm pumps seem to lose efficiency and starvation occurs. Tom

 

[TR3driver]

at very high rpms the diaphragm pumps seem to lose efficiency and starvation occurs. Tom

I agree the point certainly exists (although I don't know what it is either). It's basically similar to valve float, at some point the spring isn't strong enough to overcome the inertia of the lever & diaphragm before the cam comes around again. And unlike the valves, you can't just go to a stronger spring because that also changes the pressure.

 

[tdskip]

Interesting guys - good info.